Telnet Options

Last Updated
2011-12-01
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Registries included below

Telnet Options

Registration Procedure(s)
IETF Consensus
Reference
[RFC855]
Note
The Telnet Protocol has a number of options that may be negotiated.
These options are listed here.  "Internet Official Protocol Standards"
(STD 1) provides more detailed information.
Available Formats

CSV
Options Name Reference
0 Binary Transmission [RFC856]
1 Echo [RFC857]
2 Reconnection [DDN Protocol Handbook, "Telnet Reconnection Option", "Telnet Output Line Width Option", "Telnet Output Page Size Option", NIC 50005, December 1985.]
3 Suppress Go Ahead [RFC858]
4 Approx Message Size Negotiation ["The Ethernet, A Local Area Network: Data Link Layer and Physical Layer Specification", AA-K759B-TK, Digital Equipment Corporation, Maynard, MA. Also as: "The Ethernet - A Local Area Network", Version 1.0, Digital Equipment Corporation, Intel Corporation, Xerox Corporation, September 1980. And: "The Ethernet, A Local Area Network: Data Link Layer and Physical Layer Specifications", Digital, Intel and Xerox, November 1982. And: XEROX, "The Ethernet, A Local Area Network: Data Link Layer and Physical Layer Specification", X3T51/80-50, Xerox Corporation, Stamford, CT., October 1980.]
5 Status [RFC859]
6 Timing Mark [RFC860]
7 Remote Controlled Trans and Echo [RFC726]
8 Output Line Width [DDN Protocol Handbook, "Telnet Reconnection Option", "Telnet Output Line Width Option", "Telnet Output Page Size Option", NIC 50005, December 1985.]
9 Output Page Size [DDN Protocol Handbook, "Telnet Reconnection Option", "Telnet Output Line Width Option", "Telnet Output Page Size Option", NIC 50005, December 1985.]
10 Output Carriage-Return Disposition [RFC652]
11 Output Horizontal Tab Stops [RFC653]
12 Output Horizontal Tab Disposition [RFC654]
13 Output Formfeed Disposition [RFC655]
14 Output Vertical Tabstops [RFC656]
15 Output Vertical Tab Disposition [RFC657]
16 Output Linefeed Disposition [RFC658]
17 Extended ASCII [RFC698]
18 Logout [RFC727]
19 Byte Macro [RFC735]
20 Data Entry Terminal [RFC1043][RFC732]
21 SUPDUP [RFC736][RFC734]
22 SUPDUP Output [RFC749]
23 Send Location [RFC779]
24 Terminal Type [RFC1091]
25 End of Record [RFC885]
26 TACACS User Identification [RFC927]
27 Output Marking [RFC933]
28 Terminal Location Number [RFC946]
29 Telnet 3270 Regime [RFC1041]
30 X.3 PAD [RFC1053]
31 Negotiate About Window Size [RFC1073]
32 Terminal Speed [RFC1079]
33 Remote Flow Control [RFC1372]
34 Linemode [RFC1184]
35 X Display Location [RFC1096]
36 Environment Option [RFC1408]
37 Authentication Option [RFC2941]
38 Encryption Option [RFC2946]
39 New Environment Option [RFC1572]
40 TN3270E [RFC2355]
41 XAUTH [Rob_Earhart]
42 CHARSET [RFC2066]
43 Telnet Remote Serial Port (RSP) [Robert_Barnes]
44 Com Port Control Option [RFC2217]
45 Telnet Suppress Local Echo [Wirt_Atmar]
46 Telnet Start TLS [Michael_Boe]
47 KERMIT [RFC2840]
48 SEND-URL [David_Croft]
49 FORWARD_X [Jeffrey_Altman]
50-137 Unassigned [IANA]
138 TELOPT PRAGMA LOGON [Steve_McGregory]
139 TELOPT SSPI LOGON [Steve_McGregory]
140 TELOPT PRAGMA HEARTBEAT [Steve_McGregory]
141-254 Unassigned
255 Extended-Options-List [RFC861]

Telnet Authentication Types (Option 37)

Registration Procedure(s)
First come first served
Reference
[RFC2941]

Command

Registration Procedure(s)
First come first served
Reference
[RFC2941]
Available Formats

CSV
Command Description Reference
0 IS [RFC2941]
1 SEND [RFC2941]
2 REPLY [RFC2941]
3 NAME [RFC2941]

Types

Registration Procedure(s)
First come first served
Reference
[RFC2941]
Available Formats

CSV
Type Description Reference
0 NULL [RFC2941]
1 KERBEROS_V4 [RFC2941]
2 KERBEROS_V5 [RFC2942]
3 SPX [RFC2941][1]
4 MINK [RFC2941][1]
5 SRP [RFC2944]
6 RSA (also used by SRA) [RFC2941]
7 SSL [RFC2941]
8-9 Unassigned [IANA]
10 LOKI [RFC2941][1]
11 SSA [Steven_Schoch]
12 KEA_SJ [RFC2951]
13 KEA_SJ_INTEG [RFC2951]
14 DSS [RFC2943]
15 NTLM [Louis_Kahn][1]

KERBEROS_V4 Telnet Authentication Type (Type 1)

Registration Procedure(s)
First come first served
Reference
[RFC1411]
Available Formats

CSV
Suboption Command Reference
0 AUTH [RFC1411]
1 REJECT [RFC1411]
2 ACCEPT [RFC1411]
3 CHALLENGE [RFC1411]
4 RESPONSE [RFC1411]
5 FORWARD [Derrick_Brashear]
6 FORWARD-ACCEPT [Derrick_Brashear]
7 FORWARD-REJECT [Derrick_Brashear]
8 EXP [Thomas_Wu]
9 PARAMS [Thomas_Wu]

KERBEROS_V5 Telnet Authentication Type (Type 2)

Registration Procedure(s)
Specification Required
Reference
[RFC2942]
Available Formats

CSV
Suboption Command Reference
0 AUTH [RFC2942]
1 REJECT [RFC2942]
2 ACCEPT [RFC2942]
3 RESPONSE [RFC2942]
4 FORWARD [RFC2942]
5 FORWARD_ACCEPT [RFC2942]
6 FORWARD-REJECT [RFC2942]

SRP Telnet Authentication Type (Type 5)

Registration Procedure(s)
Specification Required
Reference
[RFC2944]
Available Formats

CSV
Suboption Command Reference
0 AUTH [RFC2944]
1 REJECT [RFC2944]
2 ACCEPT [RFC2944]
3 CHALLENGE [RFC2944]
4 RESPONSE [RFC2944]
5-7 Unassigned [RFC2944]
8 EXP [RFC2944]
9 PARAMS [RFC2944]

KEA_SJ (Type 12) and KEA_SJ_INTEG (Type 13) Authentication Types

Registration Procedure(s)
Specification Required
Reference
[RFC2951]
Available Formats

CSV
Suboption Command Reference
1 KEA_CERTA_RA [RFC2951]
2 KEA_CERTB_RB_IVB_NONCEB [RFC2951]
3 KEA_IVA_RESPONSEB_NONCEA [RFC2951]
4 KEA_RESPONSEA [RFC2951]

DSS Authentication Type (Type 14)

Registration Procedure(s)
Specification Required
Reference
[RFC2943]
Available Formats

CSV
Suboption Command Reference
1 DSS_INITIALIZE [RFC2943]
2 DSS_TOKENBA [RFC2943]
3 DSS_CERTA_TOKENAB [RFC2943]
4 DSS_CERTB_TOKENBA2 [RFC2943]

Telnet Encryption Types (Option 38)

Registration Procedure(s)
First come first served
Reference
[RFC2946]
Note
In the Telnet Encryption commands and types [RFC2946] there have been
various implementations in several widely distributed versions of
Telnet (e.g., at MIT, Stanford, and Columbia).  Originally, only two
encryption types were specified.  Additional encryption types have
been defined and are listed below.  Additions to the list are
registered by the IANA and documented here.

Command

Registration Procedure(s)
First come first served
Reference
[RFC2946]
Available Formats

CSV
Command Description Reference
0 IS [RFC2946]
1 SUPPORT [RFC2946]
2 REPLY [RFC2946]
3 START [RFC2946]
4 END [RFC2946]
5 REQUEST-START [RFC2946]
6 REQUEST-END [RFC2946]
7 ENC_KEYID [RFC2946]
8 DEC_KEYID [RFC2946]

Types

Registration Procedure(s)
First come first served
Reference
[RFC2946]
Available Formats

CSV
Type Description Reference
0 NULL [RFC2946]
1 DES_CFB64 [RFC2946]
2 DES_OFB64 [RFC2946]
3 DES3_CFB64 [RFC2946]
4 DES3_OFB64 [RFC2946]
5-7 Unassigned [IANA]
8 CAST5_40_CFB64 [RFC2946]
9 CAST5_40_OFB64 [RFC2946]
10 CAST128_CFB64 [RFC2946]
11 CAST128_OFB64 [RFC2946]
12 AES_CCM [S_Josefsson]

DES_CFB64 Telnet Encryption Type (Type 1)

Registration Procedure(s)
First come first served
Reference
[RFC2952]
Available Formats

CSV
Suboption Command Reference
1 CFB64_IV [RFC2952]
2 CFB64_IV_OK [RFC2952]
3 CFB64_IV_BAD [RFC2952]

DES_OFB64 Telnet Encryption Type (Type 2)

Registration Procedure(s)
First come first served
Reference
[RFC2953]
Available Formats

CSV
Suboption Command Reference
1 OFB64_IV [RFC2953]
2 OFB64_IV_OK [RFC2953]
3 OFB64_IV_BAD [RFC2953]

DES3_CFB64 Telnet Encryption Type (Type 3)

Registration Procedure(s)
First come first served
Reference
[RFC2947]
Available Formats

CSV
Suboption Command Reference
1 CFB64_IV [RFC2947]
2 CFB64_IV_OK [RFC2947]
3 CFB64_IV_BAD [RFC2947]

DES3_OFB64 Telnet Encryption Type (Type 4)

Registration Procedure(s)
First come first served
Reference
[RFC2948]
Available Formats

CSV
Suboption Command Reference
1 OFB64_IV [RFC2948]
2 OFB64_IV_OK [RFC2948]
3 OFB64_IV_BAD [RFC2948]

CAST5_40_CFB64 (Type 8) and CAST128_CFB64 (Type 10) Telnet Encryption Types

Registration Procedure(s)
First come first served
Reference
[RFC2950]
Available Formats

CSV
Suboption Command Reference
1 CFB64_IV [RFC2950]
2 CFB64_IV_OK [RFC2950]
3 CFB64_IV_BAD [RFC2950]

CAST5_40_OFB64 (Type 9) and CAST128_OFB64 (Type 11) Telnet Encryption Types

Registration Procedure(s)
First come first served
Reference
[RFC2949]
Available Formats

CSV
Suboption Command Reference
1 OFB64_IV [RFC2949]
2 OFB64_IV_OK [RFC2949]
3 OFB64_IV_BAD [RFC2949]

People

ID Name Contact URI Last Updated
[David_Croft] David Croft mailto:david&infotrek.co.uk 1998-09
[Derrick_Brashear] Derrick Brashear mailto:shadow&dementia.org 1995-01
[IANA] Internet Assigned Numbers Authority mailto:iana&iana.org 2012-08
[Jeffrey_Altman] Jeffrey Altman mailto:jaltman&watsun.cc.columbia.edu 2000-01
[Louis_Kahn] Louis Kahn mailto:louisk&microsoft.com 1998-10
[Michael_Boe] Michael Boe mailto:mboe&cisco.com 1998-06
[Rob_Earhart] Rob Earhart mailto:earhart+&cmu.edu 1995-04
[Robert_Barnes] Robert Barnes mailto:rab&stallion.oz.au 1997-07
[S_Josefsson] S. Josefsson mailto:jas&extundo.com
http://josefsson.org/shishi/shishi.html#Telnet%20encryption%20with%20AES-CCM
2003-11
[Steve_McGregory] Steve McGregory mailto:stevemc&pragmasys.com 1998-12
[Steven_Schoch] Steven Schoch mailto:schoch&sheba.arc.nasa.gov 1995-01
[Thomas_Wu] Thomas Wu mailto:tjw&stanford.edu 1998-09
[Wirt_Atmar] Wirt Atmar mailto:atmar&aics-research.com 1998-06

Footnote

[1]
Authentication types never submitted to the IETF for consideration as an Internet standard.